PHP: preg_split

Description

array preg_split ( string pattern, string subject [, int limit [, int flags]] )

Returns an array containing substrings of subject split along boundaries matched by pattern.

If limit is specified, then only substrings up to limit are returned, and if limit is -1, it actually means "no limit", which is useful for specifying the flags.

flags can be any combination of the following flags (combined with bitwise | operator):

PREG_SPLIT_NO_EMPTY: If this flag is set, only non-empty pieces will be returned by preg_split().
PREG_SPLIT_DELIM_CAPTURE: If this flag is set, parenthesized expression in the delimiter pattern will be captured and returned as well. This flag was added for 4.0.5.
PREG_SPLIT_OFFSET_CAPTURE: If this flag is set, for every occurring match the appendant string offset will also be returned. Note that this changes the return value in an array where every element is an array consisting of the matched string at offset 0 and its string offset into subject at offset 1. This flag is available since PHP 4.3.0 .

Przykład 1. preg_split() example : Get the parts of a search string


<?php

// split the phrase by any number of commas or space characters,

// which include " ", \r, \t, \n and \f

$keywords = preg_split("/[\s,]+/", "hypertext language, programming");

?>

Przykład 2. Splitting a string into component characters


<?php

$str = 'string';

$chars = preg_split('//', $str, -1, PREG_SPLIT_NO_EMPTY);

print_r($chars);

?>

Przykład 3. Splitting a string into matches and their offsets


<?php

$str = 'hypertext language programming';

$chars = preg_split('/ /', $str, -1, PREG_SPLIT_OFFSET_CAPTURE);

print_r($chars);

?>

will yield:

Array
(
    [0] => Array
        (
            [0] => hypertext
            [1] => 0
        )

    [1] => Array
        (
            [0] => language
            [1] => 10
        )

    [2] => Array
        (
            [0] => programming
            [1] => 19
        )

)

Notatka: Parameter flags was added in PHP 4 Beta 3.

User Contributed Notes


The following pattern will match a html tag:



<?php

  $pattern = '/(<(?:[^<>]+(?:"[^"]*"|\\'[^']*\\')?)+>)/';

?>



So the following will nicely convert a string of html to an array, where each array-item is 1 tag or text within a tag:



<?php

  $html_string = '<html><body><p class="a<weird>name">The classname is not seen as a different tag</p></body></html>';

  $html_array = preg_split ('/(<(?:[^<>]+(?:"[^"]*"|\\'[^\\']*\\')?)+>)/', trim ($html), -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);

?>



Array

(

    [0] => <html>

    [1] => <body>

    [2] => <p class="a<weird>name">

    [3] => The classname is not seen as a different tag

    [4] => </p>

    [5] => </body>

    [6] => </html>



)


<?

/************************************************************

* Author: Richard Lajaunie

* Mail : richard.lajaunie@cote-azur.cci.fr

*

* subject : this script retreive all mac-addresses on all ports

* of a Cisco 3548 Switch by a telnet connection

*

* base on the script by: xbensemhoun at t-systems dot fr on the same page

**************************************************************/



if ( array_key_exists(1, $argv) ){

    $cfgServer = $argv[1];

}else{

    echo "ex: 'php test.php 10.0.0.0' \n";

    exit;

}



$cfgPort    = 23;                //port, 22 if SSH

$cfgTimeOut = 10;



$usenet = fsockopen($cfgServer, $cfgPort, $errno, $errstr), $cfgTimeOut);



if(!$usenet){

        echo "Connexion failed\n";

        exit();

}else{

        echo "Connected\n";

        fputs ($usenet, "password\r\n");

        fputs ($usenet, "en\r\n");

        fputs ($usenet, "password\r\n");

        fputs ($usenet, "sh mac-address-table\r\n");

        fputs ($usenet, " "); // this space bar is this for long output

       

        // this skip non essential text 

        $j = 0;

        while ($j<16){

        fgets($usenet, 128);

        $j++;

        }

    stream_set_timeout($usenet, 2); // set the timeout for the fgets

    $j = 0;

        while (!feof($usenet)){

        $ret = fgets($usenet, 128);

        $ret = str_replace("\r", '', $ret);

        $ret = str_replace("\n", "", $ret);

        if  (ereg("FastEthernet", $ret)){

            echo "$ret \n";

        }

        if (ereg('--More--', $ret) ){

            fputs ($usenet, " "); // for following page

        } 

        $info = stream_get_meta_data($usenet);

        if ($info['timed_out']) {

            $j++;

        }

        if ($j >2){

            fputs ($usenet, "lo");

            break;

        }

    }

}

echo "End.\r\n";

?>


'galium at sandnarrows dot com' misunderstanded.

he wrote ' Notice the delimiters are missing', but the delimiters are not missing.

when using preg_*() functions, you need to quote pattern with 'delimiters', for example '/', '#', '@', or '(' and ')'.

in the context of preg_split(), 'the delimiters' means both,

 (A)delimiters of pattern - which quote pattern

 (B)delimiter pattern     - which split the string to array



in his first code,

<?php

  preg_split('( and | or | not )',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);

?>

the '(' and ')' is a delimiter of pattern strings(A). this is same as...

<?php

  preg_split('/ and | or | not /',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);

  // or 

  preg_split('! and | or | not !',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);

  // and so on...

?>

so, It returns: Array ( [0] => blah [1] => blarg [2] => ick ). (there is no doubt nor any bugs)

the delimiters(A) are not missing. and the delimiter pattern(B) is ' and | or | not'.



then, in the following code...

<?php

  preg_split('(( and )|( or )|( not ))',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);

?>

the first '(', and last ')' is a delimiter of pattern strings, and second, third, firth '(' and ')' make subpatterns('parenthesized expression').

this is same as...

<?php

  preg_split('/( and )|( or )|( not )/',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);

?>

and so on...

the delimiters(A) are not missing. and the delimiter pattern(B) is '( and )|( or )|( not)' ( this is same as ' (and|or|not) ').



Sorry for my bad English. ( can you understand?)

hope this can help some one.

and also hope, some one rewite this to good English.


I needed a function to highlight strings in a piece of text that could be marked up.  the task couldn't be accomplished with a single preg_replace so I wrote the code below which processes only the parts of the text _outside_ markup tags.



for example: with the text:



click on <a href="nowhere.html">nothing</a>!



I wanted to "highlight" a string (e.g. "no"), producing:



click on <a href="nowhere.html"><span class="hilite">no</span>thing</a>!



and not:



click on <a href="<span class="hilite">no</span>where.html"><span class="hilite">no</span>thing</a>!



hope this helps someone!



<?php

function hilites($search, $txt) {

    $r = preg_split('((>)|(<))', $txt, -1, PREG_SPLIT_DELIM_CAPTURE);

    for ($i = 0; $i < count($r); $i++) {

        if ($r[$i] == "<") {

            $i++; continue;

            }

        $r[$i] = preg_replace(

            "/($search)/i", "<span class='hilite'>\\1</span>", $r[$i]

            );

        }

    return join("", $r);

    }

?>


I needed to encode special html characters in strings, but keep some of the tags working! This function does the deed:

<?php

function html_out_keep_tags ($string) {

  $newstring = '';

  $pattern = '/(<\/?(?:a .*|h1|h2|b|i)>)/ims';

  $newarray = preg_split( $pattern, $string, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );

  foreach ($newarray as $element) {

    if (!preg_match($pattern, $element))

      $element = htmlspecialchars ( html_entity_decode($element, ENT_QUOTES), ENT_QUOTES);

    $newstring .= $element;

  }

  return $newstring;

}

?>

edit $pattern to change the allowed tags.

Note that ?: usefully prevents the sub-pattern from becoming a delimiter. Double encoding is prevented, see notes on htmlspecialchars().


Struggled with this today and just thought I would toss out a note in case anyone else has a problem. When using PREG_SPLIT_DELIM_CAPTURE the note about parenthesized expression is rather important.



If you do: preg_split('( and | or | not )',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);



It returns: Array ( [0] => blah [1] => blarg [2] => ick ) 



Notice the delimiters are missing.



If you put extra () in: preg_split('(( and )|( or )|( not ))',"blah and blarg or ick",-1,PREG_SPLIT_DELIM_CAPTURE);



It returns: Array ( [0] => blah [1] => and [2] => blarg [3] => [4] => or [5] => ick )


preg_split is very useful for splitting up the http common log. Sample:





<?php


$line = '10.0.0.2 - - [17/Mar/2003:18:03:08 +1100] "GET /images/org_background.gif HTTP/1.0" 200 2321 "http://10.0.0.3/login.php" "Mozilla/5.0 Galeon/1.2.7 (X11; Linux i686; U;) Gecko/20021203"';





$elements = preg_split('/^(\S+) (\S+) (\S+) \[([^\]]+)\] "([^"]+)" (\S+) (\S+) "([^"]+)" "([^"]+)"/', $line,-1,PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);





print_r($elements);


?>





Results:


Array


(


    [0] => 10.0.0.2


    [1] => -


    [2] => -


    [3] => 17/Mar/2003:18:03:08 +1100


    [4] => GET /images/org_background.gif HTTP/1.0


    [5] => 200


    [6] => 2321


    [7] => http://10.0.0.3/login.php


    [8] => Mozilla/5.0 Galeon/1.2.7 (X11; Linux i686; U;) Gecko/20021203


)


The above description for PREG_SPLIT_OFFSET_CAPTURE may be a bit confusing.



When the flag is or'd into the 'flags' parameter of preg_split, each match is returned in the form of a two-element array. For each of the two-element arrays, the first element is the matched string, while the second is the match's zero-based offset in the input string.



For example, if you called preg_split like this:



preg_split('/foo/', 'matchfoomatch', -1, PREG_SPLIT_OFFSET_CAPTURE);



it would return an array of the form:



Array(

  [0] => Array([0] => "match", [1] => 0),

  [1] => Array([1] => "match", [1] => 8)

)



Note that or'ing in PREG_DELIM_CAPTURE along with PREG_SPLIT_OFFSET_CAPTURE works as well.